The present invention relates to helmets in general and in particular to collapsible helmets including a number of segments hinged in a manner movable between an expanded operative position and a folded inoperative position.
Personnel engaged in occupations or activities with high levels of danger and therefore, high risk for accidents, are required to wear headgear to protect the wearers' heads against impact. Such headgear typically provides one of two levels of protection depending on which parts of the wearers' head are to be protected. The two levels are: (a) absorbing the impact energy which can be developed by falling or impact on the helmet; and (b) preventing penetration of sharp objects into the user's head through the activity.
Usually the safety standards are separated into these two levels. For dangerous activities, such as motorcycling, industry, construction, etc., both levels are needed. For less dangerous activities, such as bicycling, skating and other sports and games, the impact absorbing is the main requirement. Moreover, in these activities the wearer uses the helmet for long time periods and while under stress during the activity. For that reason it is recommended to provide ventilation slots and gaps, which is absolutely forbidden in helmets designed for dangerous activities.
There are two types of helmet constructions: the `half helmet` for protecting the crown of the wearer and the `full helmet` for protecting both the crown and the face of teh wearer.
Such headgear typically includes a rigid shell helmet with a flexible internal rigging for supporting the shell in spaced relation to the wearer's head and thus absorbing the impact without hurting the wearer's head. Rigid shell helmets suffer from a number of disadvantages. First, that they are relatively heavy when worn. Second, that they are inconvenient to carry when not in use. And third, they are inconvenient to store when not in use.
A number of collapsible helmets have been suggested to overcome some of these disadvantages as now described hereinbelow:
U.S. Pat. No. 3,987,495 to Holley describes a motorcycle helmet having two halves which may be detachably secured together for use or separated for easy storage. The halves come together at the central vertical plane that extends from the front of the helmet to the rear and thereby divides it into a right half and a left half that are mirror images of each other.
U.S. Pat. No. 4,587,676 to Estadella describes a collapsible helmet including two supplemental portions which are mutually joined at two pivot points. The supplemental portions rotate about the rotating points and engage one inside the other in a folded position and engage along a line which extends parallel to a line which defines the bottom perimeter of the helmet.
U.S. Pat. No. 4,827,537 to Villa describes a helmet having a plurality of segments which are interhinged for swinging movement between an expanded operating position and a collapsed non-operating position. The segments have cooperating ribs and recesses to maintain them in the expanded operating position.
U.S. Pat. No. 4,091,470 to Ryunishin describes a collapsible helmet composed of several inwardly curved fan-shaped sections. The helmet can be folded into a nested position so as to assume the size of one of the sections.
Similar helmets are disclosed in U.S. Pat. No. 3,991,422 to Saotome and U.S. Pat. No. 4,607,397 to Laxo.
Such developments suffer from a number of disadvantages including that they typically include a large number of elements and complicated mechanisms, they are cumbersome during conversion from their expanded operative positions to their folded inoperative positions and vice versa, and packages formed by the collapsible helmets are large and awkwardly shaped.
Therefore, there is a need for a collapsible helmet which overcomes the disadvantages of conventional collapsible helmets.